The Analysis And Discussion On Flux Weakening Control Of Permanent Magnet AC Servo Motor

High-performance permanent magnet AC servo motor is widely used in aerospace,equipment manufacturing,military and civilian industries,and other fields.In order to extend the operating range of permanent magnet AC servo motor and increase the power density at high speed,this paper deeply studies the weak magnetic characteristics of permanent magnet AC servo motor,simulate and optimize the parameters related to the weak magnetic performance of motor.Based on the design of a permanent magnet AC servo motor,the hardware design of the drive control system is completed,and the flux-weakening control program is compiled,the experimental verification results are given.Aiming at the permanent magnet AC servo motor with two kinds of typical permanent magnet rotor structures,the center of the voltage limit curve is within the current limit circle,comprehensive and in-depth analysis of the kind of motor flux-weakening control characteristics,the full range of mechanical and power characteristic curves from the zero speed to the weak magnetic field are obtained,the maximum power and torque points and the maximum possible field weakening range are deduced.Aiming at the motor parameters which affect the flux-weakening performance,a method of selecting permanent magnet material and designing permanent magnetic circuit under "V"type rotor structure is proposed.ANSYS MAXWELL finite element software was used to simulate the motor are factor,magnetic leakage factor,amplitude of BEMF and air gap magnetic flux.ANSYS Workbench field finite element software is used to analyze the temperature distribution of the motor during the speed limit operation of the current limit circle,and verify that the temperature rise distribution of the motor meets the national standard.The control and driving circuit of the flux-weakening drive control system are designed,and the sensor is analyzed and selected,the flux weakening control algorithm and the realization method are given.The main program,PWM interrupt program,external timer interrupt program,position detection program,flux-weakening control program and other software programs are compiled.On the basis of the analysis and discussion,a "V" type rotor structure with rated power of 12kW,rated torque of 36N·m,8 pole 12 slot fractional slot winding permanent magnet AC servo motor and drive control system was designed and manufactured.The experimental results show that the performance index of the motor and the field of flux-weakening are in accordance with the requirements,and it is consistent with the theoretical derivation.Carried out the motor temperature rise experiment,its distribution conforms to the relevant national standard stipulation.The method and discussion proposed in this paper have some guiding significance to analysis,research and design of permanent magnet AC servo motor with flux-weakening control function and drive control technology.